ORGANS OF THE BODY. 



627 



"branches they form a long and wide-meshed capillary network. Near the 

 opening of the iris a certain number of these tubules enter into the con- 

 struction of a new vascular circlet, the circulus arteriosus iridis minor (i), 

 but the greater proportion of them bend back in loops, and merge into 

 venous radicles after supplying the sphincter of the pupil. 



312. 



The veins derived from this very complex arterial system do not cor- 

 respond to its vessels 

 (fig. 584). 



The uvea is pos- 

 sessed of two sets of 

 venous canals ; of dif- 

 ferent degrees of 

 importance however. 

 The greater propor- 

 tion of blood from 

 this membrane is 

 taken up, namely, by 

 a moderate number of 

 large trunks, the vence 

 vorticosce (x) while the 

 anterior ciliary veins 

 (5) at the foremost 

 part of the choroid, 

 and especially in the 

 ciliary muscle, play 

 but a subordinate part 

 in draining these 

 parts. Veins, corres- 

 ponding to the pos- 

 terior ciliary arteries 

 do not exist. 



Let us first, then, 

 direct our attention 

 to the vence vorticosce. 



These are situated 

 in the external layer 

 of the choroid, and are 

 arranged in stellate 

 figures or vortices, 

 numerous wide venous 

 trunks converging to- 

 wards a central point. 

 Of these vascular stars 

 from four to six well- 

 developed ' examples 

 may be distinguished 

 in addition to some 

 others less perfect in 

 form and poorer in 

 radii. These several systems are connected together by transverse twigs. 

 The blood of the choriocapillaris is conducted into them by fine veins 



Fig. 584. 



